App: add API PropertyContainer::onEarlyChange()

Also add DocumentObject::signalEarlyChanged, triggered before
Document::signalChangedObject

src/App/DocumentObject.cpp

@@ -755,8 +755,7 @@ void DocumentObject::onBeforeChange(const Property* prop)
     signalBeforeChange(*this,*prop);
 }
 
-/// get called by the container when a Property was changed
-void DocumentObject::onChanged(const Property* prop)
+void DocumentObject::onEarlyChange(const Property *prop)
 {
     if(GetApplication().isClosingAll())
         return;
@@ -774,6 +773,15 @@ void DocumentObject::onChanged(const Property* prop)
         }
     }
 
+    signalEarlyChanged(*this, *prop);
+}
+
+/// get called by the container when a Property was changed
+void DocumentObject::onChanged(const Property* prop)
+{
+    if(GetApplication().isClosingAll())
+        return;
+
     // Delay signaling view provider until the document object has handled the
     // change
     // if (_pDoc)

src/App/DocumentObject.h

@@ -110,6 +110,8 @@ public:
     boost::signals2::signal<void (const App::DocumentObject&, const App::Property&)> signalBeforeChange;
     /// signal on changed  property of this object
     boost::signals2::signal<void (const App::DocumentObject&, const App::Property&)> signalChanged;
+    /// signal on changed property of this object before document scoped signalChangedObject
+    boost::signals2::signal<void (const App::DocumentObject&, const App::Property&)> signalEarlyChanged;
 
     /// returns the type name of the ViewProvider
     virtual const char* getViewProviderName(void) const {
@@ -601,6 +603,8 @@ protected:
     virtual void onBeforeChange(const Property* prop) override;
     /// get called by the container when a property was changed
     virtual void onChanged(const Property* prop) override;
+    /// get called by the container when a property was changed
+    virtual void onEarlyChange(const Property* prop) override;
     /// get called after a document has been fully restored
     virtual void onDocumentRestored();
     /// get called after an undo/redo transaction is finished

src/App/Property.cpp

@@ -28,15 +28,17 @@
 #endif
 
 #include <atomic>
+#include <Base/Exception.h>
 #include <Base/Tools.h>
 #include <Base/Writer.h>
 #include <CXX/Objects.hxx>
 
+#include "Application.h"
+#include "DocumentObject.h"
 #include "Property.h"
 #include "ObjectIdentifier.h"
 #include "PropertyContainer.h"
 
-
 using namespace App;
 
 
@@ -230,10 +232,15 @@ void Property::destroy(Property *p) {
 
 void Property::touch()
 {
+    if(GetApplication().isClosingAll())
+        return;
+
     PropertyCleaner guard(this);
-    if (father)
-        father->onChanged(this);
     StatusBits.set(Touched);
+    if (getName() && father) {
+        father->onEarlyChange(this);
+        father->onChanged(this);
+    }
 }
 
 void Property::setReadOnly(bool readOnly)

src/App/PropertyContainer.h

@@ -249,6 +249,11 @@ public:
 
 
 protected:
+  /** get called by the container when a property has changed
+   *
+   * This function is called before onChanged()
+    */
+  virtual void onEarlyChange(const Property* /*prop*/){}
   /// get called by the container when a property has changed
   virtual void onChanged(const Property* /*prop*/){}
   /// get called before the value is changed